Applicant has previously proposed cerium oxide having a powder form with a specific surface area of 0.6 m2/g or less as a deoxidizer containing cerium oxide (see Patent Literature 1). The reduced specific surface area of this type of cerium oxide prevents abrupt reaction with oxygen even when it is brought into direct exposure to the atmosphere, thus eliminating the possibility of ignition.
As seen above, reducing the specific surface area provides the advantage of preventing abrupt reaction with oxygen. However, excessive reduction in the specific surface area will give rise to a decrease in oxygen absorption rate. Therefore, what is desired is a technique of increasing the oxygen absorption rate to the extent possible while preventing abrupt reaction with oxygen.
Meanwhile, one of the primary applications of deoxidizers relates to storage of foods. Food storage not only involves storage at room temperature, but in many cases also involves storage in low-temperature environments such as in refrigerators. Accordingly, there is a demand for deoxidizers exhibiting less degradation in oxygen absorptivity even in low-temperature environments.
Patent Literature 1: WO 2007/069735 A1